i18n update

Addresses EDUCATOR-2685 in particular

2.1.16

Bump version of edx-i18n-tools to 0.4.5.

2.1.15

Fix issue with Rich Text Prompt (Educator-2634)

2.1.14

Fix issues with linkifiying submissions: EDUCATOR-2634

2.1.13

Add support for wysiwyg prompt editing and style cleanup

2.1.11

#1076

2.1.10

Merge pull request #1073 from edx/efischer/group_access_export

Efischer/group access export

2.1.9

Fix allow_file_upload default value

2.1.8

Shore up the previous release.

2.1.7

Be defensive about serializing training examples.